RESUMEN
Background: One of the nanobiotechnology concepts is application of bio systems for production of nanoparticles. Gold nanoparticles have shown many useful applications especially in medicine. Fungi are the best candidates for the synthesis of gold nanoparticles because of their ability to produce large amount of enzymes. The aim of this study was bioproduction of gold nanoparticles using Penicillium chrysogenum and its antibacterial impact on four common pathogenic bacteria was determined
Methods: Penicillium chrysogenum species isolated from effluent of Isfahan Foulad Mobarake factory. The biomasses of fungi were incubated with HAuCl[4] solution in a shaker-incubator for 72 hr, and gold nanoparticles were produced. Production of gold nanoparticles was evaluated by UV-vis spectroscopy and X-ray diffraction. Also antibacterial effect of nanoparticles and fungi extract on 4 pathogenic bacteria including Bacillus subtilis, Staphylococcus areus, Pseudomonas aeroginosa, and Escherichia coli was studied. The minimum inhibitory concentration and minimum bactericidal concentration of the nanoparticles against mentioned bacteria were determined by microdilution method
Results: Synthesis of gold nanoparticles was confirmed by observing the characteristic peak at 532 nm using UV-vis spectroscopy. The XRD analysis also demonstrated that the nanoparticles are in the form of nanocrystaline. Also, it was shown that Penicillium chrysogenum produces intracellular gold nanoparticles in spherical and triangular shapes
Conclusion: Fungus Penicillium chrysogenumis able to produce intracellular gold nanoparticles in the size range of 50-200 nm
RESUMEN
Measuring the viability of probiotic microorganisms in food products using plate count methodology is a common practice due to the simplicity [ease of performance], inexpensive and routine testing characters of this method. In present study, the suitability of de man rogosa and sharpe agar [MRS] bile agar medium for the selective enumeration of mixed probiotic bacteria [Lactobacillus acidophilus LA-5, L. casei 431 and Bifidobacterium lactis BB-12] in presence of mesophilic lactic cultures [Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. Cremoris] and yoghurt bacteria [Streptococcus thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus] was investigated. Yoghurt bacteria did not grow neither in presence of 0.15% nor 0.30% of bile salts, as was expected. Mesophilic lactic starters could grow at both concentrations of bile salts at all incubation temperatures except 37°C. According to these results, MRS-bile agar [0.15 bile salts] could be successfully used for selective enumeration of mixed probiotic cultures in presence of mesophilic culture and/or yoghurt bacteria when plates were incubated at 37°C for 72 h